Titanium dioxide is useful for pigmenting certain fiber-forming polymers which are usually spun from solutions in dimethylacetamide or dimethylformamide. Titanium dioxide is added to such a fiber-forming solution in the form of a well dispersed mixture or slurry of titanium dioxide in dimethylacetamide or dimethylformamide. It is known that up to 50 weight percent of titanium dioxide can be prepared as a slurry in dimethylacetamide or dimethylformamide (U.S. Pat. No. 2,999,839, Col. 3, line 67). From an economic viewpoint, it is advantageous to prepare titanium dioxide and dimethylacetamide or dimethylformamide slurries which contain very high concentrations of titanium dioxide because less space is required to store the slurry, more efficient use is made of mixing equipment, and better dispersion quality is achieved.